EFR Blow Off Valve Stiff Spring

Borg Warner’s alternate “stiff” CRV spring for the EFR turbochargers provides a 66% stiffer spring rate than the standard EFR spring. Designed to meet the needs of those who require a bit more clamping force at the BOV, this is the stiffest spring suitable for use with the EFR internal BOV. (Any higher stiffness than this leads to tip-out surge when lifting from part throttle).

This item is not required based on HP or boost level – most applications work fine with the standard CRV spring. For applications that have an open CRV during part throttle cruising in high vacuum (Audibly loud, such as stock engine Subaru WRX/STI with EFR6758) or if surge is present while lifting the throttle – this stiffer spring may be the solution.

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